Majority of Coronary Heart Disease Patients Have At Least 1 of 4 Major Risk Factors

At least 1 of the 4 major risk factors for coronary heart disease (CHD) – hyperlipidemia, hypertension, diabetes, and smoking – is present in 80% or more of patients with CHD, according to the findings from 2 separate prevalence studies.

“These results challenge claims in the medical literature that CHD events commonly occur (as often as 50% of the time) in persons who have not been exposed to at least 1 major risk factor,” writes Philip Greenland, MD, of Northwestern University, Chicago, Illinois, United States, and colleagues.

They analysed the prevalence and consistency of major risk factors for CHD from 3 major studies – the Chicago Heart Association Detection Project in Industry (35,642 men and women aged 18 to 59 years), the Multiple Risk Factor Intervention Trial (347,978 men aged 35 to 57 years), and a population based sample (3295 men and women aged 34 to 59 years) from the Framingham Heart Study. The investigators determined fatal CHD in all cohorts as well as non-fatal myocardial infarction in the Framingham Heart Study compared with exposures to 4 major risk factors – total cholesterol of 240mg/dL or higher, systolic/diastolic blood pressure of at least 140/90 mm Hg, diabetes, and cigarette smoking. Overall follow up lasted 21 to 30 years.

Among the 20,995 fatalities from CHD, 87 to 100% of the individuals had at least 1 of these major risk factors. When stratified by sex and age the data showed that 87.0 to 92.7% of men aged 40 to 59 years at baseline, and 90.2 to 93.8% of same aged women who died from CHD had at least 1 of the major risk factors.

Among Framingham Heart Study patients aged 40 to 59 years at baseline, 91.6% of men and 87.2% of women who experienced a non-fatal myocardial infarction had at least 1 major risk factor.

A secondary analysis of risk factors including serum cholesterol greater than or equal to 200 mg/dL, systolic/diastolic blood pressure higher than 120/80 mm Hg, current use of antihypertensive or cholesterol lowering medication, current smoking, or diabetes revealed between 96% and 100% of patients with fatal CHD and between 84.6% and 100% of patients with non-fatal myocardial infarction had at least 1 of these higher than favourable risk factors.

“Overall,” Dr. Greenland and colleagues conclude, “these data indicate that prior estimates of the relative infrequency of major risk factor exposures among coronary CHD cases were probably incorrect.”

Another study conducted by Umesh N. Khot, MD, Cleveland Clinic Foundation, in Ohio, United States, and colleagues analysed the prevalence of conventional risk factors – cigarette smoking, diabetes, hyperlipidemia, and hypertension – for CHD data from 122,458 patients enrolled in 14 international clinical trials. They found that among patients with CHD at least 1 risk factor was prevalent in 84.6% of women (mean age 66.1 years) and 80.6% of men (mean age 59.9 years).

Dr. Khot’s group found that only 9.4% of women and 11.4% of men aged 45 years and younger have none of the 4 conventional risk factors for CHD.

“Our study indicates that in patients with CHD,” Dr. Khot and colleagues write, “conventional risk factors were present at a much higher prevalence than commonly believed.” The authors note that intense focus on the 4 conventional risk factors and the lifestyle behaviours causing them, rather than on patients lacking conventional risk factors, has great potential to decrease coronary heart disease.

Related Study: “Prevalence of Conventional risk Factors in Patients With coronary Heart Disease”. JAMA 2003 290:898-904.
JAMA 2003;290:891-897.